Lewis, 37 years old and a veteran of 17 NFL seasons, now has to decide whether the Ravens’ victory Sunday will also be the final game of his Hall of Fame career.

A magnetic resonance imaging test taken Monday on Lewis’ right arm revealed the Ravens’ worst fear: a torn triceps, which is a rare but significant injury that will likely require surgery and an arduous six-month recovery period.

Selected after offensive tackle Jonathan Ogden in the first round of the Ravens’ first draft in 1996, Lewis has become the face of the franchise, one of the NFL’s most respected players, and one of the most celebrated linebackers ever.

Lewis always has been non-committal about retirement, saying only that he’ll know when it’s time. Ravens coach John Harbaugh declined to speculate on whether Lewis may have played his last game.

“That’s for Ray to speak on,” Harbaugh said. “I admire Ray Lewis. I’ve said that many times. I think everybody in this room does. Everybody that knows him feels that way about him. I’m looking forward to seeing what Ray says about that.”

The Ravens are expected to put both Lewis and Lardarius Webb, their top cornerback who tore the anterior cruciate ligament in his left knee in the first quarter Sunday, on injured reserve as early as Tuesday, ending their seasons. Their losses further deplete a defense that is ranked an uncharacteristic 26th overall in the NFL and has allowed more than 200 yards rushing in back-to-back games for the first time in franchise history.

“I would rather not characterize my emotions because I’m disappointed for those guys,” said Harbaugh whose team is 5-1 , tied with the Houston Texans for the best in the AFC. “It doesn’t matter how I or someone else feels about it. It’s their thing. These are guys who put so much effort, heart and soul into what they do.”

Harbaugh was given the news by Ravens’ head trainer Mark Smith just before 4 p.m. Monday . He hadn’t spoken to Lewis as of Monday afternoon, but Harbaugh sensed in his conversations with Lewis following Sunday’s game that it could be a serious injury. Lewis was getting treatment after the game and not available to reporters.

“He was worried about it,” Harbaugh said. “He said some things about his faith. He goes back to his faith, and he said some things that I’ll never forget. You look at his situation and what he’s accomplished and what he’s accomplished and what he was hoping to accomplish this year. He’s going to have to accomplish those things in different ways because that’s the way it’s gone. He puts his faith in providence. That’s where he’s going to go with that.”

Lewis has absorbed some of the criticism because of the struggles of the normally stout defense despite leading the team with 57 tackles through six games. Lewis made many of those tackles down the field as critics pointed out that he was having a hard time getting off blocks and chasing down running backs.

He made a game-high 14 tackles Sunday and his takedown of Tanner came after a 6-yard gain at the 2-minute warning. Lewis immediately shook his right arm before heading to the sidelines, where he watched the remainder of the game. Lewis took a knee to watch the game’s final frantic moments, which included a dropped two-point conversion by Dallas wide receiver Dez Bryant that would have tied the game, and a missed 51-yard field goal by Dan Bailey that would have won it.

“It's a devastating blow. He's the heart of the defense,” said Ravens linebacker Dannell Ellerbe, one of several players who will be asked to occupy bigger roles in Lewis’ absence. “There's nothing that I can say that people don't know. It really hurts to lose a guy like Ray Lewis.”

“Ray Lewis has helped progress this game so guys like myself have something to strive to be...a professional. Prayers sent up,” Griffin said.

Woodley, one of the Ravens’ biggest rivals, said “Hate hearing that because he’s one of the NFL’s true legends.”

Lewis is signed with the Ravens through 2015 and several people close to him Monday said that they would be surprised if the ultra competitive linebacker went out on this note. He had dropped about 20 pounds before the season to get down to 235, his lightest weight since his rookie season, to adapt better to a pass-happy NFL.

“First of all I know he ain't going to go out like that. Ray Lewis will come back from this injury,” Ellerbe said. “To have a 17-year career, to compete at that level that he competed at and be in shape, for the game to be so dangerous, just for him to be in the league 17 years and have the accolades he's got, it speaks for itself. To be labeled as the best linebacker to ever play the game, it's truly a blessing.”

NFL Hall of Famer Deion Sanders, one of Lewis’ former teammates and closest friends, said on Twitter that “The Ray Lewis I know will not end his career off this injury. He’s conquered much more than this. He will determine when it’s over, not [an] injury.”

Still, Lewis faces a potentially long recovery. While speaking about triceps tears in general and not specifically about Lewis, Dr. Daryl Osbahr, an attending orthopedic surgeon and the director of sports medicine research at Med Star Union Memorial Hospital, said full tears usually require surgery and a recovery period of about six months.

“With complete ruptures, they require surgery for athletes who want to return to play at the prior level of their competition,” said Osbahr. “Obviously, with a football player, you’d want to fix it so they’d have strength in their elbow. That would mean basically missing the season if it’s a complete season … There’s plenty of time to get back for the season next year. These processes of the triceps are definitely under a year so pretty much at six months, you expect them to be ready to go.”